1. Field of the Invention
This invention relates to new colored pigments and aims generally to improve the same and to provide novel processes for the production thereof.
2. Description of the Prior Art
In the prior art organic color pigments have been employed in particles of light reflective size; i.e. the so-called pigmentary range of 0.2 to 0.4 micron, by forming or reducing the inorganic color pigment to such size and dispersing it directly into the medium in which it was to be employed. Patents also exist which disclose the surface treatment of such organic color pigments with various chemical substances to aid dispersion, but these substances are largely retained on the color particles and limit their usefulness and compatibility with many vehicles.
The prior art had also disclosed certain advantages obtainable by incorporating a vehicle-soluble linear polymer or copolymer with an organic pigment, specifically that method contained in U.S. Pat. No. 3,133,893, wherein a vehicle soluble linear polymer or copolymer is formed in the presence of an organic pigment obtained from an organic pigment presscake that has been dispersed by stirring in the presence of a dispersing agent such as stearamidopropyldimethylhydroxyethyl ammonium chloride, cetyl pyridinum chloride, sodium dodecyl sulfonic acid, ethylene oxide-acid condensation products, bis(2-ethylhexyl) sodium sulfosuccinate; and certain advantages obtainable, as in U.S. Pat. No. 3,423,358, by the preformation of crosslinked polymeric particles which are subsequently dyed. Both of these patents present certain failings or shortcomings in actual use, viz:
U.S. Pat. No. 3,133,893 is concerned with producing a color masterbatch for use in spinning solutions, in which masterbatch the pigment particles are presscake particles which, because of their relatively large sizes, nonsphericity and crystalline structure, produce coloring deviations and are used inefficiently; the coated particles are removable by filtration without precoagulation, which requires that they be of substantial size, namely of the order of 40 microns or more and their coating must dissolve in the medium of use to be adapted to the patentee's purpose. In addition very large quantities of water are required and wasted in the patented process and the dispersants used become waste of the process.
U.S. Pat. No. 3,423,358 is concerned with the production of colored organic filler material by dyeing a preformed crosslinked insoluble polymer particle. Its process is essentially restricted to the use of water soluble dye structures or those capable of being applied to the crosslinked filler particles in water soluble form and of thereafter being insolubilized on the surface of said polymer particles. This requirement excludes most of the high light-fastness organic pigmentary compounds and generally speaking the tinctorial strength obtained is rather low. The patented process necessitates the introduction of an expensive and sometimes complicated dyeing step, and also makes substantial use of water both for the dyeing and washing steps.